Internal combustion engines

ABSTRACT

An internal combustion engine including a cylinder head having a passage positioned therein adapted to communicate with a combustion chamber and adapted to carry either a fuel-air mixture or products of combustion. The passage has first and second portions positioned at an angle to one another that are formed by a pair of retractable dies during a casting process thereby leaving a sharp discontinuity. A valve seat insert is positioned in one portion of the passage and it includes a lip having an inner surface which curves or tapers smoothly toward this discontinuity to improve the gaseous flow characteristics of the passage.

United States Patent Josey Feb.8,1972

[54] INTERNAL COMBUSTION ENGINES 211 App]. 110.; 40,011

[30] Foreign Application Priority Data Aug. 7, 1969 Great Britain ..39,606/69 [52] U.S.Cl. ..-......l23/l88S [51] Int. Cl ..F0ll 3/22, F011 3/06 [58] FieldofSearch ..l23/l88 S, 188 M, 188 AF, 188 VA [56] References Cited UNITED STATES PATENTS 2,424,738 7/1947 Bronander ..l23/188 S FOREIGN PATENTS OR APPLICATIONS 1,352,656 l/1964 France ..123/l88S 882,706 11/1961 Great Britain ..123/l88 S Primary ExaminerMark M. Newman Assistant Examiner-R. B. Rothman Attorney-.Iohn R. Faulkner and Keith L. Zerschling [57] ABSTRACT An internal combustion engine including a cylinder head having a passage positioned therein adapted to communicate with a combustion chamber and adapted to carry either a fuel-air mixture or products of combustion. The passage has first and second portions positioned at an angle to one another that are formed by a pair of retractable dies during a casting process thereby leaving a sharp discontinuity. A valve seat insert is positioned in one portion of the passage and it includes a lip having an inner surface which curves or tapers smoothly toward this discontinuity to improve the gaseous flow characteristics of the passage.

6 Claims, 5 Drawing Figures 3,640,261 SHEET UF 2 F'IG.3

INVENTOR GEOFFKZVA'. JOJZ') Z/ of ATTORN s INTERNAL COMBUSTION ENGINES BACKGROUND OF THE INVENTION This invention relates to internal combustion engines which have a die-cast cylinder head.

Where induction or exhaust passages are formed in a cylinder head with a pair of retractable dies, it is difficult to avoid the formation of a sharp edge or discontinuity in the wall of the induction or exhaust passage where the dies meet during the casting process. These sharp edges or discontinuities formed by a diecasting process are shown in detail in U.S. Pat. Nos. 2,767,694 and 2,968,015.

SUMMARY OF THE INVENTION According to the invention, an internal combustion engine has the following features:

a. an induction or exhaust passage from one side of a cylinder head to a combustion chamber is formed in a diecasting process by a pair of retractable dies so that a wall of the passage has a sharp discontinuity at the intersection of the dies during the casting process; and

b. an induction or exhaust valve seat insert is formed with a lip which extends into the induction or exhaust passage to the discontinuity and tapers or curves smoothly towards the discontinuity to improve the gaseous flow characteristics of the induction or exhaust passage.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a fragmentary sectional view of an internal combustion engine cylinder head embodying the invention;

FIG. 2 is a view of the cylinder head of FIG. 1 looking in the direction of the arrow A with the valve seat inserts removed;

FIG. 3 shows the profile of the induction passage at line 3- 3 of FIG. 1;

FIG. 4 is a plan view of the valve seat insert; and

FIG. 5 is a side view of the valve seat insert.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 is a section along one of the induction passaged of an overhead camshaft internal combustion engine with four cylinders in line. The engine is of a monoblock construction in that the cylinder head and the cylinder block 11 are formed integrally. The cylinder head-cylinder block is an aluminum alloy die casting. The camshaft and valve gear (not shown) are mounted in a separately die cast camshaft carrier 12 which is electron beam welded to the cylinder head-cylinder block casting along the line 13.

While the description below deals with only one induction passage 14 and cylinder 15, it should be understood that the remainder are identical, and that the invention has equal applicability and utility with an exhaust passage.

The cylinder head--cylinder block casting is manufactured using retractable sliding dies. During the diecasting process, a first sliding die extends into the cylinder bore 15 and into the valve seat end of the induction passage 14 up to lines 16 and 17 in FIG. 1 to form both the cylinder bore and a first portion or inner end of the induction passage. A second sliding die extends into the induction passage 14 from the side of the cylinder head to form a second portion of the induction passage that is positioned at an angle with respect to the first portion. The portion of the second die which extends into the induction passage 14 has a D-shaped cross section, as shown in FIG. 3, with its fiat surface forming the lower wall 18 of the second portion of the induction passage.

The first die is withdrawn down the cylinder bore and the second die is withdrawn outwardly in the direction of the arrow C shown in FIG. 1. It will be appreciated that with such dies a sharp edge or discontinuity in the walls of the induction passage 14 at the intersection of the first and second portions along the line 17 is inevitable because any shaping of the dies to smooth the discontinuity would prevent their withdrawal.

An inlet valve seat 19 made of sintered metal, e.g., copperiron, having a ring 20 is positioned in an interference fit in the casting. The insert is formed with a lip 21 which extends up to the edge 22 in the wall of the induction passage. The outer surface 23 of the lip 21 is shaped to follow closely the wall of the induction passage and the inner surface 24 is shaped so that the lip tapers smoothly towards the edge 21 to reduce the discontinuity in the wall of the induction passage and thereby improve the flow characteristics of the induction passage.

The lip 21 extends for a substantial arcuate length of the ring 20 and the inner surface 24 may comprise an inner toroidal-type surface which intersects and blends smoothly into the valve seat 25 positioned on the ring. Additionally, the upper surface 26 of the lip 21 opposite the ring 20 may form a continuation of the second portion of the induction passage 14, and as shown in FIG. 1, it may be in the plane of lower flat wall 18.

The D-shaped section of the induction passage increased the cross-sectional area of the passage compared to a circular or oval section and provides a flat lower wall which permits a The invention may equally well be applied to die-cast cylinder heads which are formed separately from the cylinder block in the conventional manner.

In order to clarify the drawings, the exhaust passage and valve seat have been omitted, but as stated above, the exhaust valve seat may also be provided with a lip to improve flow characteristics in the exhaust passage.

lclaim:

I. An internal combustion engine comprising a cylinder head having a passage positioned therein, said passage having a first portion, and a second portion positioned at an angle with respect to said first portion and formed by a pair of retractable dies whereby the wall of the passage has a sharp discontinuity formed during the casting process at the intersection of said first portion and said second portion, said second portion of said passage having a flat or planar wall surface adjoining the discontinuity, one end of said first portion being adapted to communicate with a combustion chamber, a valve seat insert positioned in said end of said first portion,

said valve seat insert including a lip extending into said first portion to said sharp discontinuity at the intersection of said first and second portions of said induction passage, said lip including an inner surface that tapers curves smoothly toward the discontinuity to improve the gaseous flow characteristics of the passage.

2. The combination of claim 1 in which said valve seat insert comprises a ring having a beveled surface adapted to receive the seating face of a valve, the inner surface of said lip tapering smoothly into said beveled surface.

3. The combination of claim 2 in which said lip extends for a substantial arcuate portion of said ring.

4. The combination of claim 3 in which the surface of said lip opposite said ring forms a continuation of the wall of said second portion of said induction passage.

5. The combination of claim 1 in which said valve seat insert comprises a ring having a beveled surface adapted to receive the seating face of a valve, the inner surface of said lip tapering smoothly into said beveled surface, said lip extending for a substantial arcuate portion of said ring and the surface of said lip opposite said ring lies in the plane of said flat or planar wall surface of said second portion of said passage.

6. An internal combustion engine comprising a cylinder head having a passage positioned therein, said passage having a first portion, and a second portion positioned at an angle with respect to said first portion and formed by a pair of retractable dies whereby the wall of the passage has a sharp discontinuity formed during the casting process at the intersection of said first portion and said second portion, said second portion of said passage having a flat or planar wall surface adjoining the discontinuity, one end of said first portion being adapted to communicate with a combustion chamber, a

and meets said beveled surface of said ring and tapers curves smoothly toward the discontinuity to improve the gaseous flow characteristics of the passage, said surface of said lip opposite said ring lying in a plane formed by said flat or planar wall surface of said second portion of said passage. 

1. An internal combustion engine comprising a cylinder head having a passage positioned therein, said passage having a first portion, and a second portion positioned at an angle with respect to said first portion and formed by a pair of retractable dies whereby the wall of the passage has a sharp discontinuity formed during the casting process at the intersection of said first portion and said second portion, said second portion of said passage having a flat or planar wall surface adjoining the discontinuity, one end of said first portion being adapted to communicate with a combustion chamber, a valve seat insert positioned in said end of said first portion, said valve seat insert including a lip extending into said first portion to said sharp discontinuity at the intersection of said first and second portions of said induction passage, said lip including an inner surface that tapers curves smoothly toward the discontinuity to improve the gaseous flow characteristics of the passage.
 2. The combination of claim 1 in which said valve seat insert comprises a ring having a beveled surface adapted to receive the seating face of a valve, the inner surface of said lip tapering smoothly into said beveled surface.
 3. The combination of claim 2 in which said lip extends for a substantial arcuate portion of said ring.
 4. The combination of claim 3 in which the surface of said lip opposite said ring forms a continuation of the wall of said second portion of said induction passage.
 5. The cOmbination of claim 1 in which said valve seat insert comprises a ring having a beveled surface adapted to receive the seating face of a valve, the inner surface of said lip tapering smoothly into said beveled surface, said lip extending for a substantial arcuate portion of said ring and the surface of said lip opposite said ring lies in the plane of said flat or planar wall surface of said second portion of said passage.
 6. An internal combustion engine comprising a cylinder head having a passage positioned therein, said passage having a first portion, and a second portion positioned at an angle with respect to said first portion and formed by a pair of retractable dies whereby the wall of the passage has a sharp discontinuity formed during the casting process at the intersection of said first portion and said second portion, said second portion of said passage having a flat or planar wall surface adjoining the discontinuity, one end of said first portion being adapted to communicate with a combustion chamber, a valve seat insert positioned in said end of said first portion, said valve seat insert including a ring having a beveled surface adapted to receive the seating face of a valve, a lip extending for a substantial portion of said ring and extending into said first portion to said sharp discontinuity at the intersection of said first and second portions of said induction passage, said lip including an inner toroidal-type surface that extends into and meets said beveled surface of said ring and tapers curves smoothly toward the discontinuity to improve the gaseous flow characteristics of the passage, said surface of said lip opposite said ring lying in a plane formed by said flat or planar wall surface of said second portion of said passage. 